Ignition apparatus



Sept. 27, 1949.

T. TOGNOLA ETAL.

IGNITION APPARATUS Filed July l. 1944 I I I I I I I I I I I I I I JBY I N VEN TORS.

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AFITTOFINEY Patented Sept. 27, 1949 c l2,482,884 n IGNITION ArPAnA'r-US'- f f'runio frognola, Sidney, ana-Mame-s;;f1jiiprn,

0n'eo'nta,':N: Y., assignorfs tomBendix'Avla-tion Corporation, New-York, N. Yffacorporation of VDelaware- Application-Jiy 1, 194418,;ser'ia1No;543,136

(ciels-45W 1s claims. L 11j This invention 'relates to 'ignition apparatus andv more 'par'tieul'arlylto Yai kcombined spark plug and coil :unit adaptedf'or u'sei'n the ignition system of lanv` internal combustion engine;

One'ofqthe objects yof the present invention'is vtopro'vide a novel simpliiied ignition unit'v compri'sing'a transformer V.anda spark plug.

. `.notlierobjectisl tdprov'idea unit of the above E'eliaracter)whichA is small .and compact, and yet durable and 'r'efliablev in operation.

vStill `another .Objectis to provide a novel ignition coilof smallsize which may be incor- .dporatedf ina .standardfshielded spark plug by making a minimum nunberoff alterations .in the latter.V A A f y :A further-objectjisto'prvide novelmeans for f connecting iaflowvoltage.supplylead yto the termi- `nal of aspark plugthrough themedium of a high =frequen-cy transformer coil.V

:Astillgfurtherfobject isto incorporate a trans- :formercoilg-in a shielded spark.` plug in-a novel manner-so as tominimize danger of flashovers.

' Anotherl objectl is to'provide a novel ignition coil-which Will .'Withstandthe high temperatures :.towhich itiis subjected -infa shielded spark'plug.

TheV above andfurther'objects` and: novel features of the invention will'more"fullyxappearfrom ith'e'ffollow-irig detaileddescription' when the 'same .iszreadY inf-onnection with the accompanying drawings. It is to be expressly understood, however, that the drawings are-.fon the purpose "of i1- f 'lustrationfonlyand'are not intended tojdeine. the f limits ofthe' inventiongreference for this latter purpose." being hadfprimarilyV to the appended K claims Y In the` drawings,- whereinlike `1 reference charactors? refer t'o: like parts yithro'ughoutthe several views; v v

yFig". 1 isa-half sectional elevation viewof one ,i

form of ignition unit embodying'V the present in- '.vention; and,

Fig. 2 ,is an' enlarged: scale detail View, partly Y"diagramrxlatic, showing'the coil of,A the unit of Fig. 1.

' `'rhei'mfention is illustrated inthe drawings, by .Wayof .example only, .as embodying a radio .shielded'spark plu'g`of the type now in common Ause on aircraft andsimilar engines `and more par- Yticula'rlyof.the type disclosed'L in the cop'ending application of Tullio Togno1a,. Serial No. 494,516, filed July 13, 1943, now Patent No. 2,453,049. In the embodiment shown, the'spark plug comprises a. tubular metallic shell I0 which isexternally threaded at I.I for cooperationrwith a threaded opening-man engine cylindermot shown). The 1 .-borethrough .shell Ill is provided with a. tapered zwalllportion I2. for purpose to hereinafter ap- .fpear.r A ground electrode I3 whichk may .be of any suitable knownY construction is securedY in the lowerfendio'f shell I-'0 by means of silver solder or any *other` suitable means.

'Groundelectrode I3 is in cooperative V,spark gap relation with the enlarged head portion I4 Y1of aV center electrode I5- which constitutes part of` the conducting Vmeans''mounted inthe differentialzbore I6,y I7 of'a ceramic or like insulator Y I'8`jvfor conductingl hightension electrical current therethrough. `'Ihe-upper end of spindle I9 of the center'ele'ctrod'eis provided with Vone or more annular grooves" or equivalent deformations which are engaged by arsolid insulating compound or 'cement 2Q, whereby the center electrode lis heldin' place. Embeddedinslli'ng compound Zli'andv heldjthereby'in a likemann'er isa tennina'lplugillj.` `,The rcenter electrode'andplug 2| are preferably' electrically connected by a ne wireconductor '22'.

The center electrodeassembly is preferably mounted in shell: I0 inisuch'a manner as "to vprevent any' gasjlleakagefbetweeninsulator I3v and said shell. iIhe'n-lounting is effectedl by wedging "ai sleeve 2r3o'frelativelysoft metal, such as copper; between4 a surface of insulator YI 8, thatv may be coatedwitli'a thivnla'y'e'r of powdered4 graphite Wall of theinsulatorlm'ay alsobe provided With a ifslignmaperg Extending `upwardly from sneu VIn Q beyond the `en'do`f `insulator l`I 8 is a metallic shield- 'inglbarrelZA 'which maybe integral with or otherwise"operativelysecured vtothe shell.' The inner diameter' of said barrel' is preferably larger than thefinnerdiani'eter ofshell Ig'thereby forming .spar-k plug now in common' use.

, al ShoulderK 25.

bularl core 26 ofmagnetic metal. This core preferably-'butffnoty necessa'rily'consists ofk a few spiral Vturnsgofv sheet metal, suchas magnetic steel, forming .a laminated'tubewhich will extend over Ltheup'p'rend' of4 insulator I8 into the annular l rspace'..betweentl'ie insulator andbarrel 24.

k.'[nor'der ,to guard against flashoversof high tensioric`ur1"ent the ends of core 26 should be kept.ar1 safeldistance from grounded parts of the spark plug. V Additionally,fthe.metal of said core maybe coatedwith athin lmof suitableelectricalinsulation,v such. as enamel.

@ne` or more layersv 2l of.` insulating material )are .placed orwound around core .26 andl .a secondary'cOil Winding 2,8 is then .applied theretol the several layers ofthe coil winding-being separated ina'wellknown' manner by` layers ofinfsl'atingshreet rmaterial 21a'. Apriniary Windso" ing'l29, .Whichmayfco'nsist ofa single layer, is

Y layer of secondary winding not shown in the drawings.

. of the spark plug.

alsace-i wound around the last insulated layer of the secondary winding and is in turn surrounded by an insulating layer or sleeve 30. Surrounding this latter layer and insulated from barrel 24 by a sleeve or layer 3l is a split sleeve 32 of magnetic metal which acts as a path for magnetic fluxV in conjunction with core 26. Sleeve 32 -is preferably split longitudinally, as .at 32a,jin order to avoid a short circuit path for eddy currents I 28 is connected, such as by a thin strip conductor terminal 2l in a manner to The inner or high potential 28 is kept relatively short so that it will be a safe distance from the grounded metallic parts of the structure and the length of the other layers are progressively in- 34, to the spark plug hereinafter appear.

K creased. This novel construction makes it possible to incorporate the necessary number of turns in the winding While keeping, the turns which are at the highest potential at a safe distance from grounded parts of the unit.

The end of the outer or low potential layer of the secondary winding 28 is connected to the Vadjacent end of primary winding 29, as lat 35.

Either end of primary winding 29 is connected to A an input terminal 36 to be hereinafter described and the other end thereof is connected to ground by connecting it to the barrel 24, as at 31, through a conductor 38. The spaces between the insulating layers 2l, 21a., 3B and 3| and preferably the l entire coil structure are impregnated or filled with a suitable insulating compound such as polymerized cashew-nut-shell oil or the like. In the interest of clarity, this filling compound is The lling or impregnation of the coil unit may be done under vacuum or by pressure and vacuum means well known in the art. The insulating layers 21, 21a

f are preferably of a high heat resisting flexible sheet material, such as woven glass bre cloth impregnated with a suitable insulating compound, such as silicon. Insulating layers 30 and 3l may be of the same material or any other suitable high heat resisting insulating material.

Projecting into the upper end of the coil unit 28, 29 is an insulating block 39 which has a flange which rests upon the upper end of insulating 'sheet 2l, 21a. Molded or cemented into the inner end of block 39 is a terminal 40 to which connector 34 may be permanently connected. A spring 4l or other suitable means may be provided for connecting terminal 40 to terminal 2l The input terminal 35 is mounted in the outer end of block 39 and is connected through a radial passage 42 by lead 43 to the ungrounded end of primary winding 29.

The coil assembly may be held in place in barrel 24 by a flanged tubular member 44. The fiange of said member rests on shoulder 45 in barrel 24 and the end of the latter peened or rolled inwardly over the flange. The joint is then soldered or made weather tight in some other suitable manner. The outer end of mem- Y ber 44 is externally threaded for Vreceiving a ,spark plug barrel.

4 (not shown )which may be of standard size and knownv construction.

Either before or after adapter member 44 is secured in place the space within barrel 24 around and inside the coil unit may be filled with a suitable insulating compond, such a polymerized cashew-nut-,shell oil and a drying agent as disclosed in Tognola U. S. Patent No. 2,348,427. The compound should be so treated as to set from a liquid to a solid mass of a resilient, non-moldable mixture. In its liquid form', the compound may be inserted by pressure after evacuating the Some of the proposed filling compound is illustrated at 46 but the entire space is not shown in filled condition since it would tend to obscure the remaining structure. In any event,

the filling compound is not essential.

There is thus provided Va novel ignition unit which is simple and compacta novel unit which, when incorporated in a low voltage distribution ignition system, will eliminate all high tension leads, thereby materially reducing vthe possibilities of ignition failures and the radio shielding requirements. A novelly wound transformer coil is also provided'whereby the danger ofvflashovers Within such a unit is minimized. 4'Additionally, the novel unitprovided is not appreciably larger than'standard radio shielded spark plugs and may be used in lieu thereof on engines already designed and built.

Although only a single embodiment of the invention is illustrated and fdescribed it is to be expressly understood that thesame is not limited thereto. For example, differently constructed spark plugs, such as those having mica insulation instead of ceramic, may be used. Various other changes not heretofore mentioned may also be made, particularly in the design and arrangement of parts illustrated and in the materials mentioned without departing from the spirit and scope of the invention as will now be clear to those skilled in the art.

- Vassembly mounted insaid shell, a metallic shielding barrel extending from said shell around and beyond the projecting end of said assembly, an ignition coil in said barrel and surrounding the outer end of said assembly, and means operatively electrically connecting said coil and the electrode of said assembly.

2. In apparatus of the class described, a tubular metallic shell, an insulated center electrode assemblymounted in said shell, a metallic shielding barrel extending from said shell around and beyond the projecting end of said assembly, a transformer coil comprising primary and secondary windings in said barrel, said coil extending into the annular space around said assembly, and means for electrically connecting saidsecondary Winding to the electrode of said assembly.

3. In apparatus of the class described, a tubular metallic shell, an insulated center electrode assembly mounted in said shell, a metallic shielding barrel Vextending from said shell around and beyond the projecting end of said assembly, a transformer coil in said barrel, said coil comprising atubular metallic core surrounding the outer end of said assembly, and meansfor operatively connecting said coil to the electrode of said assembly. f

4. In apparatus of the class described, a tubular metallic shell, an insulated center electrode assembly mounted in said shell, a metallic shielding barrel extending from said shell around and beyond the projecting end of said assembly, an ignition coil comprising primary and secondary windings in said barrel, a tubular metallic core for said coil surrounding the Aouter end of said assembly, and a split sleeve of magnetic metal surrounding said coil.

5. In apparatus of the class described, a tubular metallic shell, an insulated center electrode assembly mounted in said shell, a metallic shielding barrel extending from said shell around and beyond the projecting end of said assembly, a transformer coil in said barrel surrounding the outer end of said assembly, said coil comprising a tubular core of magnetic metal, a secondary winding on said core and a primary winding around said secondary winding, and means for connecting the high potential end of said secondary winding to the electrode of said assembly.

6. A combined spark plug and coil unit comprising a tubular body member, an insulated electrode assembly mounted in said member and projecting therefrom, a shielding tube extending from said member around and beyond said assembly, an ignition coil having primary and secondary windings extending into the annular space between said assembly and tube, said secondary winding lcomprising a plurality of layers which progressively increase in length from the inner layer to the outer layer, and means for electrically vconnecting said inner layer to the electrode of said assembly.

'7. A combined spark plug and coil unit comprising a tubular body member, an insulated electrode assembly mounted in said member and projecting therefrom, a shielding tube extending from said member around and beyond said assembly, a transformer coil comprising primary and secondary windings slidably extending into the annular space between said assembly and tube, the number of turns in each layer of said secondary winding increasing progressively from the inner layer to the outer layer of said secondary winding, a magnetic ux path comprising a tubular metallic core within said secondary winding and a split metallic sleeve surrounding said primary winding, and means for electrically connecting said secondary winding to the electrode .of said assembly.

8.. A combined spark plug and coil unit comprising a tubular body member, an insulated electrode assembly mounted in said member and projecting therefrom, a shielding tube extending from said member around and beyond said assembly, an ignition coil in said tube, insulating means between successive layers of said coil and extending beyond the ends .of said layers for spacing said coil from opposite ends of said tube, and means for closing the ends of said barrel.

9. A combined spark plug and coil unit comprising a tubular body member, an insulated electrode assembly mounted in said member and projecting therefrom, a shielding tube extending from said member around and beyond said assembly, a tubular coil unit including a secondary Winding, a primary winding on said secondary winding, insulating sheets between adjacent layers of said windings and extending substantially beyond the ends vof said layers for spacing said windings from the ends of said barrel, an insulatingV block in one end of said coil unit and terminals in opposed ends of said block, one of said terminals being connected to said primary winding and the other of said terminals being connected to said secondary winding, and means for connecting said other terminal to the electrode of said assembly.

10. A combined spark plug and coil unit comprising a tubular body member, an insulated electrode assembly mounted in said member and projecting therefrom, a shielding tube extending from said member around and beyond said assembly, a tubular coil unit slidably extending into said tube around said assembly, said coil unit including primary and secondary windings and insulating sleeves between adjacent layers of said windings and extending beyond the ends of said layers, insulating means extending transversely across the ends of said coil unit, and means secured in the open end .of said tube for holding said coil unit in place and for receiving a shielded supply cable.V

l1. An ignition unit comprising a spark plug of the type wherein a shieldingrbarrel surrounds and extends beyond an insulated center electrode, a tubular transformer coil unit slidably extending into the annular space in said barrel around the end of said insulated electrode, and means connectingY the secondary Winding of said coil unit to said electrode.

12. An ignition unit comprising a spark plug of the type wherein a shielding barrel surrounds and extends beyond an insulated center electrode, a tubular ignition coil unit comprising primary and secondary windings, insulating means disposed between the layers of the coil and extended for spacing said windings from opposite ends of said barrel, and means for connecting the high potential end of said secondary winding to said electrode.

13. An ignition unit comprising a spark plug of the type wherein a shielding barrel surrounds and extends beyond an insulated center electrode, a tubular ignition coil unit slidably extending into said barrel, insulating means disposed between the layers of said coil unit and extended for spacing the windings of said coil unit from the ends of said barrel, an insulating block having terminals in opposite ends thereof, means for connecting one of said terminals to the primary winding of said coil unit, means for connecting the Aother of said terminals to the secondary winding of said coil unit, and means for connecting said other terminal to said electrode when said coil unit is inserted in said barrel.

TULLIO TOGNOLA. MAURICE S. THORN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,081,979 Bentley June 1, 1937 2,180,358 Hooven Nov. 21, 1939 2,236,316 Helgason Mar. 25, 1941 2,266,614 Robinson Dec. 16, 1941 2,378,893 Berkey June 26, 1946 Certificate of Correction Patent N o. 2,482,884 September 27, 1949 TULLIO TOGNOLA ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column l, line 52, for Patent N o. 2,453,049 readA Patent No. 2,453,048; and that the said Letters Patent should be read with thisecorrection therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 7th day of February, A.D. v1950.

THOMAS F. MURPHY,

Assistant ommzssz'oner of Patents. 

